JP4110892B2 - Engine control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an engine control device having a cylinder deactivation mechanism, and more particularly to a process in a case where an abnormality occurs in a return operation from a cylinder deactivation state.
[0002]
[Prior art]
From the standpoint of improving fuel efficiency, an engine having a cylinder deactivation mechanism that deactivates some of the cylinders is known. Hereinafter, a state in which some cylinders are deactivated is also referred to as a “reduced cylinder state”. In general, in order to deactivate a cylinder, in response to a cylinder deactivation instruction from an ECU (Engine Control Unit), at least one of an exhaust valve and an intake valve of the designated cylinder is closed and fuel is supplied to the cylinder. This is done by stopping.
[0003]
However, after the cylinder deactivation instruction is given, the exhaust valve or the intake valve may not perform deactivation properly for some reason. For example, a variable valve mechanism of a type that opens and closes a valve by a hydraulic circuit includes a mechanism that inserts a lock pin or the like with a hydraulic pressure to a mechanism that opens and closes the valve to switch between a movable state and a resting state of the valve. In such a case, the valve may not be correctly deactivated immediately after the cylinder deactivation instruction due to a change in hydraulic pressure or a shift in the insertion timing of the lock pin. Such a failure in switching the state of the valve can occur not only in the variable valve mechanism using a hydraulic circuit. A similar problem can occur when returning a cylinder once paused to an operating state. In other words, the valve may not immediately start operating despite the return instruction.
[0004]
In the reduced-cylinder state, on the premise that intake and exhaust are not performed because the valve is closed in the idle cylinder, an amount of air corresponding to the number of cylinders to be operated is supplied to the other cylinders. Therefore, if an abnormality in the deactivation operation or the reversion operation occurs, such as when the cylinder to be deactivated is operating or the valve to be deactivated is deactivated, combustion is not performed correctly, and an emission abnormality may occur. In addition, problems such as a decrease in drivability due to misfire or a torque step, or deterioration of the catalyst due to an abnormality in the mixing ratio may occur.
[0005]
From such a point of view, in an engine having a cylinder deactivation mechanism, when performing cylinder deactivation, a method of stopping fuel supply to the deactivation cylinder after the intake valve and exhaust valve of the cylinder have been completely stopped has been proposed. (For example, refer to Patent Document 1).
[0006]
Incidentally, as a document showing the level of the technical field, there is Patent Document 2 which discloses ignition timing control during a reduced cylinder operation of a variable cylinder engine.
[0007]
[Patent Document 1]
JP 2001-140664 A
[Patent Document 2]
JP-A-7-63148
[0008]
[Problems to be solved by the invention]
On the other hand, in an engine having an electronically controlled combustion injection control device, fuel cut control for stopping fuel injection is performed when the vehicle is in a decelerating running state, for the purpose of reducing emissions and reducing fuel consumption. However, in an engine having a cylinder deactivation mechanism, when fuel cut is performed at the same time when an abnormality occurs in the intake valve when returning from the deactivation state of the cylinder, unignited fuel and air flow to the exhaust side, There is a possibility of causing overheating by reacting with the catalyst.
[0009]
The present invention has been made in view of the above points, and in an engine having a cylinder deactivation mechanism, it is possible to prevent overheating of the catalyst even when an abnormality occurs when the cylinder returns from the deactivation state. It is an object to provide a simple engine control device.
[0010]
[Means for Solving the Problems]
In one aspect of the present invention, a cylinder deactivation mechanism And a catalyst device provided in the exhaust passage, When there is a fuel cut request when returning from the cylinder deactivation state, the fuel cut process is prohibited until the completion of the return from the cylinder deactivation state. To prevent intake air including unignited fuel and air from being supplied to the catalytic device. The control means to perform is provided.
[0011]
The engine has a cylinder deactivation mechanism that selectively deactivates some of the plurality of cylinders, and the engine control device controls switching between a deactivation state and an operation state of the cylinder. Here, when a fuel cut request is generated when the cylinder is returned from the inactive state to the active state, the fuel cut is prohibited until the cylinder is returned to the inactive state, that is, until the cylinder completes the transition to the active state. To do.
[0012]
When returning from the cylinder inactive state, if the intake valve malfunctions and temporarily stops operation, the fuel injected during the intake valve abnormality does not flow into the combustion chamber. Stay in the intake passage. When the intake valve operates normally in the next cycle, the fuel staying in the intake passage in the previous cycle flows into the combustion chamber. At the same time, when the fuel cut is executed, the fuel and a large amount of air that are not accompanied by the combustion injected in the previous cycle are discharged to the exhaust side by the fuel cut. As a result, there is a risk that the catalyst reacts with excess fuel and air, resulting in overheating and the like. Therefore, when a fuel cut request is made at the time of return of the deactivated cylinder, it is possible to prevent the above problem from occurring by prohibiting the fuel cut until the return process is completed.
[0013]
In one aspect of the engine control apparatus, the control means has a predetermined return condition from the cylinder deactivation state. Established Sometimes the recovery start means for starting the return process of the deactivated cylinder, the determination means for determining completion of the return process, and after the start of the return process, the fuel cut execution condition is Established If this is detected, execution means for executing fuel cut after completion of the return processing can be provided. Thus, control is performed so that the fuel cut is executed only after the completion of the return process is determined.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Preferred embodiments of the present invention will be described below with reference to the drawings.
[0015]
[Engine configuration]
First, an engine having a cylinder deactivation mechanism, to which the present invention is applied, will be described. FIG. 1 is an overall configuration diagram of an engine according to an embodiment of the present invention. Air necessary for combustion of the engine 50 is filtered by the air cleaner 102, passed through the throttle body 105, and distributed to the intake pipe 113 of each cylinder by the surge tank (intake manifold) 111. The intake air flow rate is adjusted by a throttle valve 106 provided in the throttle body 105 and measured by an air flow meter 104. The intake air temperature is detected by an intake air temperature sensor 103. Further, the intake pipe pressure is detected by the vacuum sensor 112.
[0016]
The opening of the throttle valve 106 is detected by a throttle opening sensor 109. When the throttle valve 106 is in the fully closed state, the idle switch 110 is turned on, and the throttle fully closed signal, which is the output thereof, becomes active. An idle speed control valve (ISCV) 108 for adjusting the air flow rate during idling is provided in the idle adjustment passage 107 that bypasses the throttle valve 106.
[0017]
On the other hand, the fuel stored in the fuel tank 115 is pumped up by the fuel pump 117 and injected into the intake pipe 113 by the fuel injection valve 121 through the fuel pipe 119. In the intake pipe 113, such air and fuel are mixed, and the mixture is sucked into the engine body, that is, the cylinder (cylinder) 1 through the intake valve 123. In the cylinder 1, the air-fuel mixture is compressed by a piston and then ignited by an igniter and a spark plug to explode and burn to generate power.
[0018]
The ignition distributor 143 has a crank angle sensor 145 that generates a reference position detection pulse every 720 ° CA in terms of its axis, for example, converted to a crank angle (CA), and a reference position detection pulse every 30 ° CA. A crank angle sensor 147 is provided for generating. Further, the engine 50 is cooled by the cooling water guided to the cooling water passage 149, and the cooling water temperature is detected by the water temperature sensor 151.
[0019]
The combusted air-fuel mixture is discharged as exhaust gas to the exhaust manifold 127 through the exhaust valve 124 and then led to the exhaust pipe 129. The exhaust pipe 129 is provided with an A / F sensor 131 that detects the air-fuel ratio (A / F) of the exhaust gas. Further, a catalytic converter 133 is provided in the exhaust system downstream from the exhaust system. The catalytic converter 133 has a three-way catalyst that simultaneously promotes oxidation of unburned components and reduction of nitrogen oxides in the exhaust gas. Contained. Thus, the exhaust gas purified by the catalytic converter 133 is discharged into the atmosphere.
[0020]
Note that the engine 50 is assumed to be an engine with an EGR (exhaust gas recirculation device) for the purpose of reducing NOx (nitrogen oxide), and between the exhaust system and the intake system downstream of the throttle valve 106. Is provided with a passage 125 for circulating the exhaust gas. The gas recirculation amount is adjusted by an EGR valve 126 provided in the middle of the passage.
[0021]
The engine electronic control unit (ECU) 60 is a microcomputer system that executes fuel injection control, ignition timing control, idle rotation speed control, and the like.
[0022]
The fuel injection control is basically performed based on an intake air amount per one rotation of the engine calculated from an intake air flow rate measured by the air flow meter 104 and an engine rotation speed obtained from the crank angle sensor 145. In order to achieve the air-fuel ratio, the fuel injection amount, that is, the injection time by the fuel injection valve 121 is calculated, and fuel is injected when a predetermined crank angle is reached.
[0023]
The fuel injection control executed by the ECU 60 includes fuel cut control. The fuel cut control is executed in various states while the vehicle is running, and for example, a fuel cut during deceleration for temporarily stopping fuel injection, a fuel cut during high rotation, a maximum speed fuel cut, and the like are performed. Conditions for performing fuel cut are determined in advance. The ECU 60 monitors output signals from various sensors, assumes that a fuel cut request has been made when predetermined fuel cut conditions are satisfied, and gives a fuel cut instruction to the fuel injection valve 121 to stop fuel injection.
[0024]
As the various fuel cuts, for example, in the case of fuel cut during deceleration, it is determined that the fuel supply is in an unnecessary deceleration state when the throttle valve is fully closed and the engine speed is equal to or higher than a predetermined value. Then, the fuel injection is stopped to improve the fuel consumption, purify the exhaust gas, and prevent the catalyst from being heated. Also, in the case of high-speed fuel cut, the fuel injection is stopped at a predetermined rotational speed (for example, 8000 rpm) or more to prevent engine damage due to the engine speed increasing to the red zone or higher. It is to suppress. Further, in the case of the fastest fuel cut, the fuel injection is stopped when, for example, the vehicle speed is 180 km or more and the engine rotation speed is 4500 rpm for a predetermined time. In the present invention, all fuel cut requests are targeted regardless of conditions and reasons.
[0025]
Next, the cylinder deactivation mechanism will be described. As shown in FIG. 2, the engine 50 includes a plurality of cylinders. In the example of FIG. 2, the engine 50 includes 8 cylinders (# 1 to # 8), cylinders # 1 and # 7, cylinders # 2 and # 8, cylinders # 3 and # 5, and cylinders # 4 and # 6. Operate in pairs. That is, even in the reduced cylinder state, at least one cylinder of each set operates. Note that the firing order of the eight cylinders is the order of cylinders # 1 → # 8 → # 4 → # 3 → # 6 → # 5 → # 7 → # 2. The left four cylinders (# 1, # 3, # 5, # 7) in FIG. 1 are called the first bank, and the right four cylinders (# 2, # 4, # 6, # 8) are called the second bank.
[0026]
Exhaust gas from each cylinder is discharged to the exhaust pipe 129 and sent in the direction of arrow 80. Each exhaust pipe 129 is provided with the A / F sensor 131 and the catalytic converter 133 as described above.
[0027]
As described above, the ECU 60 controls the overall operation of the engine 50 based on outputs from various sensors. In addition, the ECU 60 supplies a control signal 72 to the variable valve mechanism of each cylinder to perform opening / closing control of the intake valve and the exhaust valve of each cylinder.
[0028]
The cylinder is deactivated by the ECU 60 closing the intake valve and exhaust valve of the target cylinder and stopping the fuel injection into the intake passage of the cylinder. More specifically, the ECU 60 first controls the variable valve mechanism to close the exhaust valve, then stops fuel injection, and then controls the variable valve mechanism to close the intake valve. As a result, usually, exhaust gas remains in the combustion chamber during cylinder deactivation. On the other hand, when returning from the cylinder deactivation state, the ECU 60 first opens the exhaust valve, then starts fuel injection, and then opens the intake valve.
[0029]
Next, a variable valve gear that controls the opening and closing of the intake valve and the exhaust valve of each cylinder will be described. 3 and 4 show the structure of a variable valve operating apparatus controlled by a hydraulic circuit. FIG. 3 is a perspective view of the variable valve operating apparatus, and FIG. 4 is a side sectional view thereof.
[0030]
As shown in FIG. 4, the variable valve operating apparatus includes a camshaft 10 provided with a cam 11. Below the cam 11, a rocker arm 21 pivotally supported by the rocker shaft 20 is provided. An arm 22 is formed on the tip side of the rocker arm 21 so as to protrude forward. The distal ends of the arms 22 are in contact with the upper ends of the pair of engine valves 13 and are pressed toward the side where the valves 13 are closed by the urging force of the valve springs. The engine valve 13 is driven to open and close based on the pressing of the arm 22 that is swung as the rocker arm 21 is pivoted about the rocker shaft 20.
[0031]
As shown in FIGS. 3 and 4, a movable cam follower 23 corresponding to the cam 11 is disposed on the upper surface of the rocker arm 21. The movable cam follower 23 is slidably disposed in a slide hole 35 (FIG. 4) formed along the vertical direction of the rocker arm 21. The movable cam followers 23 are always urged toward the cam 11 by the urging force of a coil spring (not shown). Therefore, the movable cam follower 23 receives the pressing while making sliding contact with the cam 11.
[0032]
A cylinder hole 36 is formed below the rocker arm 21 so as to intersect the sliding hole 35 into which the movable cam follower 23 is fitted. A lock pin 31 for selectively fastening or releasing the locker arm 21 and the movable cam follower 23 is slidably disposed in the cylinder hole 36.
[0033]
Next, the cam switching mechanism configured around the lock pin 31 will be described in detail with reference to FIGS. 5 (a) and 5 (b). 5 (a) and 5 (b) are cross-sectional views showing the side cross-sectional structure in the vicinity of the lock pin 31, FIG. 5 (a) shows a state when the fastening is released, and FIG. Each of the embodiments is shown.
[0034]
As described above, the movable cam follower 23 is slidably fitted into the slide hole 35 that penetrates the rocker arm 21 up and down. Further, a cylinder hole 36 intersecting with the sliding hole 35 is formed below the rocker arm 21, and a lock pin 31 is slidably fitted therein. The lock pin 31 is always urged by the coil spring 33 toward the base end side of the rocker arm 21, that is, in a direction away from the movable cam follower 23.
[0035]
A groove 32 is formed in the lock pin 31 from the center to the tip side. The lower end of the movable cam follower 23 can be fitted into the groove 32. Furthermore, the bottom surface of the front end side of the groove 32 is cut away to allow the movable cam follower 23 to slide in the vertical direction. On the other hand, the bottom surface of the central portion side (base end side) of the groove 32 is left so as to be in contact with the lower end of the movable cam follower 23.
[0036]
A space 34 on the proximal end side of the rocker arm 21 in the cylinder hole 36 and defined by the lock pin 31 is a hydraulic chamber into which hydraulic oil for operating the lock pin 31 is introduced. The hydraulic chamber 34 is connected to an oil passage 49 formed in the rocker arm 21. Further, the oil passage 49 is connected to an oil passage 43 formed in the rocker shaft 20, and hydraulic pressure in the hydraulic chamber 34 is adjusted by supplying and discharging hydraulic oil through the oil passages 43 and 49. The The lock pin 31 moves in the cylinder hole 36 in accordance with the balance between the force based on the hydraulic pressure in the hydraulic chamber 34 and the biasing force of the coil spring 33, and the position shown in FIG. Slide back and forth between the positions shown in b).
[0037]
When the fastening between the rocker arm 21 and the movable cam follower 23 is released, the hydraulic oil is discharged from the hydraulic chamber 34 to reduce the hydraulic pressure in the chamber 34. As a result, the lock pin 31 moves toward the proximal end side of the rocker arm 21 by the urging force of the coil spring 33, and is positioned at the position shown in FIG. At this time, since the lower end portion of the movable cam follower 23 is located at a portion where the bottom surface of the groove 32 of the lock pin 31 is cut out, sliding in the vertical direction is allowed.
[0038]
On the other hand, when the rocker arm 21 and the movable cam follower 23 are fastened, hydraulic oil is supplied to the hydraulic chamber 34 to increase the hydraulic pressure in the hydraulic chamber 34. As a result, the lock pin 31 moves to the distal end side of the rocker arm 21 against the urging force of the coil spring 33 and comes to a position shown in FIG. At this time, the lower end portion of the movable cam follower 23 comes to be located in a portion where the bottom surface of the groove 32 of the lock pin 31 is left. At this time, when the movable cam follower 23 is pushed down, the lower end surface thereof contacts the bottom surface of the groove 32.
[0039]
The pressing of the cam 11 at this time is directly transmitted to the rocker arm 21 through the contact of the movable cam follower 23 and the lock pin 31. In other words, the movable cam follower 23 and the rocker arm 21 at this time are connected to each other and rotate together. In this case, the rocker arm 21 is rotated by the cam 11, and the engine valve 13 is also opened and closed by the cam 11.
[0040]
Therefore, the ECU 60 controls the operation and stop of the engine valve 13 by controlling the supply of hydraulic oil to the hydraulic chamber 34 by controlling an electromagnetic valve or the like provided in the hydraulic circuit of the variable valve device. Can do.
[0041]
[Relationship between pause / return operation abnormality and exhaust]
Next, the relationship between abnormal operation of the cylinder deactivation mechanism and exhaust will be described. FIG. 6 shows the relationship between the abnormal operation state during the cylinder deactivation operation and the state in the cylinder and the influence on the exhaust in each state. Since it is during the resting operation, the ECU 60 controls the variable valve gear so that both the exhaust valve and the intake valve are closed. Therefore, the exhaust valve and the intake valve are normal if the exhaust valve and the intake valve are in a closed state, and abnormal if they are operating. In this case, it is assumed that the fuel injection is stopped in response to the cylinder deactivation instruction from the ECU 60.
[0042]
Referring to FIG. 6, state 1-1 is a state in which the exhaust valve is properly closed, but the intake valve is operating (ie, opening / closing operation). Accordingly, since the combustion gas that should be confined in the combustion chamber of the cylinder to be deactivated (which is also referred to as “deactivated cylinder”) flows back to the intake side and flows into the other cylinders, a large amount of EGR (Exhausted Gas Recirculation) is generated in the other cylinders. ) Occurs, and the exhaust becomes rich.
[0043]
In the state 1-2, since the intake valve is closed, no fresh air is sucked into the combustion chamber, and the exhaust valve is open, so that the exhaust gas is exhausted to the exhaust side. When the exhaust gas is exhausted, a negative pressure is generated in the combustion chamber. However, since the intake valve is closed, exhaust gas does not reach the other cylinders, and the idle cylinders do not suck in fresh air from other cylinders, so both the idle cylinders and the other cylinders have a particularly bad influence. Absent.
[0044]
In the state 1-3, since both the intake valve and the exhaust valve are operating, it is the same as the normal operation state, and exhaust and intake are repeated. In this case, since the deactivated cylinder to be deactivated sucks in fresh air for the other cylinders, the intake air amount in the other cylinders decreases, and as a result, the exhaust becomes rich. In addition, immediately after canceling the resting state, fresh air in the combustion chamber of the resting cylinder is discharged to the exhaust side as it is, so that it is temporarily in a lean state.
[0045]
Next, the abnormal operation at the time of return of the cylinder that has been stopped will be described. FIG. 7 shows the relationship between the abnormal operation state during the return operation of the cylinder that has been stopped, and the state in the cylinder and the effect on exhaust in each state. Since it is at the time of return, the ECU 60 controls the variable valve gear so that both the exhaust valve and the intake valve are activated. Therefore, the exhaust valve and the intake valve are normal if they are operated to open and close, and abnormal if they are stopped in a closed state. In this case, it is assumed that fuel injection and ignition are executed in response to a cylinder return instruction from the rest state.
[0046]
In state 2-1, the exhaust valve has started operating correctly, but the intake valve is still at rest. Since the intake valve is closed, fresh air corresponding to the cylinders that are at rest flows to the other cylinders, so that the exhaust becomes lean. In addition, fuel accumulation occurs in the intake passage (port) due to the execution of fuel injection. Therefore, after that, when the intake valve starts to operate correctly, excess fuel accumulated in the intake passage (port) flows into the combustion chamber, and the exhaust gas temporarily becomes a rich state of strength.
[0047]
In state 2-2, the exhaust valve remains still and the intake valve is operating correctly. Fuel injection and ignition are performed and combustion gas is generated in the combustion chamber. However, since the exhaust valve remains closed, exhaust is not performed and the combustion gas flows backward to the intake side. Since the back-flowing combustion gas flows into the other cylinders, a large amount of EGR is entered, and the other cylinders are short of intake air and the exhaust becomes rich.
[0048]
In the state 2-3, both the exhaust valve and the intake valve are still closed. Therefore, as in the case of the state 2-1, since the intake valve is closed, the fresh air corresponding to the cylinders that are at rest flows to the other cylinders, and the exhaust gas enters a lean state. In addition, fuel accumulation occurs in the intake passage (port) due to the execution of fuel injection. Therefore, after that, when the intake valve starts to operate correctly, excess fuel accumulated in the intake passage (port) flows into the combustion chamber, and the exhaust gas temporarily becomes a rich state of strength.
[0049]
As described above, when the cylinder is deactivated and when the deactivated cylinder is restored, the exhaust gas is affected according to the abnormal state of the intake valve and the exhaust valve (the respective states shown in FIGS. 6 and 7). Therefore, by detecting an abnormal state of the exhaust gas using the A / F sensor 131 or the like, it is possible to determine which state of abnormality has occurred.
[0050]
As described above, when the intake valve temporarily becomes abnormal when the cylinder is returned from the resting state, the excess fuel accumulated in the intake passage (port) after the abnormality of the intake valve is resolved thereafter. Flows into the combustion chamber (states 2-1 and 2-3 in FIG. 7). At this time, if fuel cut is executed at the same time, fuel and a large amount of air that are not accompanied by combustion injected in the previous cycle are discharged to the exhaust side. Therefore, the catalytic converter 33 on the exhaust side can react due to excess fuel resulting from abnormality of the intake valve and fresh air due to fuel cut, and can cause overheating. Therefore, in this embodiment, such a reaction of the catalyst is prevented in the reduced-cylinder operation return process described below.
[0051]
[Reduction from reduced cylinder operation]
FIG. 8 shows a flowchart of the reduced cylinder operation return processing. This process is a process for prohibiting fuel cut when returning a cylinder that has been in a paused state until now, and the ECU 60 basically monitors the outputs of various sensors to perform cylinder return processing and fuel cut execution. The timing is adjusted.
[0052]
Referring to FIG. 8, first, ECU 60 determines whether or not a specific cylinder is in a reduced cylinder operation (step S1). If the reduced-cylinder operation is being performed, the ECU 60 next determines whether or not a return condition from the resting state is satisfied (step S2). Normally, the reduced-cylinder operation is performed when the vehicle is traveling at a relatively high rotational speed with gears such as third gear and fourth gear. Accordingly, the return condition can be, for example, that the gear is shifted to the second speed when the driver steps on the accelerator pedal, or that the rotational speed is lower than the predetermined rotational speed. However, in the present invention, the return condition from the reduced cylinder state is not limited to these.
[0053]
When the return condition is satisfied (step S2; Yes), the ECU 60 determines whether or not a fuel cut request is generated (step S4). The fuel cut request is generated when various preset fuel cut conditions are satisfied as described above. Even when a fuel cut request is generated, the ECU 60 prohibits the fuel cut (step S5). As described above, if there is an abnormality in the intake valve while returning from the cylinder deactivation state, excess fuel accumulates in the intake passage, and if the intake valve operates normally in the next cycle, Since the fuel staying in the passage flows into the combustion chamber, if fuel cut is performed at the same time, fuel and a large amount of air injected in the previous cycle are discharged to the exhaust side and the catalyst reacts. Because there is a possibility.
[0054]
Then, the ECU 60 determines whether or not the cylinder return is completed (step S7). Completion of cylinder return can be determined by several methods. For example, as shown in FIG. 7, it can be determined by monitoring the exhaust state. That is, if an abnormality occurs in the intake valve or the exhaust valve when the cylinder is returned, the effect appears in the exhaust gas. Therefore, the abnormality can be determined by monitoring the exhaust state using the A / F sensor 131 of the engine 50 or the like. For example, a predetermined A / F value is set as a threshold value, and it is determined that the exhaust gas has become richer or leaner than the threshold value, is determined to be abnormal, and the recovery is performed when the recovery of the state is detected. It can be determined that it has been completed. Instead, for example, when the lift valve of each cylinder is provided with a lift sensor that can directly detect the lift amount of the valve, the lift amount of the intake valve and the exhaust valve is directly set. It may be determined that the return has been completed when no abnormality has occurred during the return.
[0055]
Thus, the ECU 60 prohibits fuel cut until it is confirmed that the cylinder has been returned. Thus, as described above, if an abnormality occurs in the intake valve during the return of the cylinder and the state 2-1 or 2-3 shown in FIG. 7 is reached, the excess fuel and the fuel cut air It is possible to prevent the catalyst from causing a reaction. When the return of the cylinder is confirmed (step S6; Yes), the ECU 60 permits fuel cut (step S7). When it is determined in step S1 that the reduced-cylinder operation is not being performed, when it is determined that the return condition is not satisfied in step S2, and when the fuel cut request is not made in step S4, all The process ends.
[0056]
In the process shown in FIG. 8, it is not necessary to detect the abnormality of the intake valve by prohibiting the fuel cut regardless of whether the abnormality of the intake valve has actually occurred during the return of the deactivated cylinder. The control is focused on safety.
[0057]
【The invention's effect】
In the present invention, at the time of return from the reduced cylinder operation, fuel cut is prohibited until the return process is completed. Therefore, excess fuel due to an intake valve abnormality during cylinder return and fresh air due to fuel cut are discharged to the exhaust side at the same time. Can be prevented from causing the reaction.
[Brief description of the drawings]
FIG. 1 shows a schematic configuration of an engine in an embodiment of the present invention.
FIG. 2 is a view for explaining a cylinder deactivation mechanism of the engine according to the embodiment of the present invention.
FIG. 3 is a perspective view showing a schematic configuration of a variable valve operating apparatus.
4 is a side sectional view of the variable valve operating apparatus shown in FIG. 3. FIG.
5 is a side sectional view of a cam switching mechanism of the variable valve operating apparatus shown in FIG.
FIG. 6 is a chart showing a relationship between an abnormal state of the intake valve and the exhaust valve during exhaust and exhaust.
FIG. 7 is a chart showing the relationship between the abnormal state of the intake valve and the exhaust valve and the exhaust when returning from the rest state.
FIG. 8 is a flowchart of reduced cylinder operation return processing.
[Explanation of symbols]
1 cylinder
13 Engine valve
21 Rocker Arm
23 Movable cam follower
31 Lock pin
50 engine
29 Exhaust pipe
56 A / F sensor
60 ECU

Claims (2)

In an engine control device having a cylinder deactivation mechanism and a catalyst device provided in an exhaust passage ,
When in demand for fuel-cut at the time of return from the cylinder deactivation state, by inhibiting the process of recovery completion to said fuel cut from the cylinder deactivation state, the intake air containing the fuel and air unreacted ignition the catalytic converter An engine control device comprising control means for preventing supply . The control means includes
Return start means for starting the return processing of the idle cylinder when a predetermined return condition from the cylinder idle state is satisfied ;
Determination means for determining completion of the return process;
2. The apparatus according to claim 1, further comprising: an execution unit configured to execute a fuel cut after the completion of the return process when it is detected that a fuel cut execution condition is satisfied after the start of the return process. Engine control device.

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